Leg axis correction with ConforMIS iForma (interpositional device) in unicompartmental arthritis of the knee.

Degeneration of the meniscus and the articular cartilage in unicompartmental osteoarthritis of the knee results in progressive deformity of the leg axis. It is the aim of this study to evaluate if a leg axis correction can be achieved by implanting a customised metallic interpositional device for the knee (ConforMIS iForma). Before and after implanting a ConforMIS iForma knee implant, a radiological analysis of the leg axis deviation in the frontal plane was performed prospectively in 27 patients by evaluating anteroposterior single-leg stance radiographs. We achieved a sufficient leg axis correction with an average correction of 3.8 degrees and an averaged small under-adjustment of 0.9 degrees by inserting the ConforMIS iForma interpositional knee implant. Apart from the primary treatment objective of articular surface restitution the ConforMIS iForma knee implant can be reliably used to correct axis deformity occurring with unicompartmental osteoarthritis of the knee.